Get news by email Potassium can work with graphite in a potassium-ion battery, claims Oregon State University, which said the last time this possibility was explored was in 1932.
“For decades, people have assumed that potassium couldn’t work with graphite or other bulk carbon anodes in a battery,” said chemist Xiulei Ji. “That assumption is incorrect. It’s really shocking that no one ever reported on this issue for 83 years.”
That said, potassium is a big atom to get into graphite.
In ‘Carbon electrodes for K-ion batteries‘, a paper in the Journal of the American Chemical Society, Ji describes a potassium-graphite cell where “graphite shows moderate rate capability and relatively fast capacity fading” in which potassium reversibly enters graphite in stages with a K:C atom ratio of 2:72, then 3:72 and finally 9:72.
To get over limited cycle life, the team moved away from graphite and synthesised a soft carbon that exhibits “cycle ability and rate capability much superior to that of graphite”, said the University.
But it is still not as good as lithium-carbon
“It’s safe to say that the energy density of a potassium-ion battery [see graph] may never exceed that of lithium-ion batteries,” said Ji. “But they may provide a long cycling life, a high power density, a lot lower cost, and be ready to take the advantage of the existing manufacturing processes of carbon anode materials.”
The hope is that potassium could replace rare and expensive lithium – according to Ji, potassium is 880 times more abundant in the Earth’s crust than lithium – as a charge carrier in batteries for transportation, industry power backup, micro-grid storage, renewable energy storage. Sodium and magnesium are other proposed lithium replacements.
Potassium can work with graphite in a potassium-ion battery, claims Oregon State University, which said the last time this possibility was explored was in 1932.
